1. Field
Apparatuses consistent with exemplary embodiments relate to a light emitting device package, a light source module, a backlight unit, a display apparatus, a television set, and an illumination apparatus.
2. Description of the Related Art
A light emitting diode (LED), a type of semiconductor light emitting device, is a semiconductor device capable of generating light of various colors according to a recombination of electrons and holes at p and n type semiconductor junctions when current is applied thereto. Compared with a filament-based light emitting device, a semiconductor light emitting device has various advantages such as a long lifespan, low power consumption, excellent initial driving characteristics, high vibration resistance, and the like, so demand for the semiconductor light emitting device continues to grow. LEDs using group III-V compound semiconductors have been recently used. In particular, recently, group III-nitride semiconductor LEDs capable of emitting light in a short-wavelength blue light has come to prominence. A group III nitride compound semiconductor is a direct transition semiconductor, and may be stably operated at a high temperature, as compared to other semiconductors, and has therefore been widely applied to luminous elements, such as LEDs or laser diodes. Such nitride compound semiconductors are also commonly used as white light sources in various kinds of devices in various fields such as keypads, backlights, traffic lights, as well as for airport runway landing lights and spotlights, and the like.
This practical use of LEDs in various fields has brought about the importance of light source units including such LEDs. In particular, a light source unit for efficiently emitting heat generated in a light emitting element such as an LED to the outside is desirable, as a resin part or lens unit encapsulating the light emitting element may be degraded and this defect may become more serious with the use of high-power light emitting elements in a case in which the heat emitted by the light emitting element can not be efficiently discharged.
Light source modules used for an LCD backlight, or the like, conventionally employed cold cathode fluorescent lamps (CCFLs). However, CCFLs use mercury gas, having disadvantages in that it has a slow response speed and low color reproducibility (or a color gamut) and is not suitable for a light, thin, short, and small LCD panel. In comparison, LED backlights are environmentally-friendly, have a fast response speed in the range of a few nano-seconds to fit a high speed response and are thus effective for a video signal stream, are available for impulsive driving, have a color gamut of 100% or higher, can have a luminance, color temperature, or the like which are changeable by adjusting the quantity of light emitted by red, green and blue LEDs, and are suitable for a light, thin, short, and small LCD panel. As such, LEDs have been actively employed as light source modules for backlights.
However, as light emitting diodes are a point light sources, hot spots may occur from backlight modules employing LEDs, whereby it may be difficult to provide uniform illumination with respect to the emitting surface of the backlight module